1. Field of the Invention
The present invention relates to laser aiming lights for firearms and, more particularly, to temperature compensating circuitry for maintaining the power level of a laser diode and associated components irrespective of changes in ambient temperature and to a removable fire and power mode selection switch..
2. Description of Related Art
Conventional manually operated firearms have had since time immemorial mechanical sights for aiming the firearm. These sights require the user to visually align the sights with a target. Because of the slight angular deviations encountered in aligning mechanical sights, accuracy is compromised well short of the meaningful range of accuracy of the firearm and the associated projectile. To increase the range of accuracy, telescopic sights have been employed to obtain an effective range of accuracy of several hundred yards and which is, in part, a function of the muzzle velocity and type of firearm. Irrespective of whether mechanical sights or telescopic sights are used, the required visual alignment with the target creates a potentially life-threatening situation in a combat environment. That is, due to underbrush or other obstacles, visual alignment may not be quickly possible and the firearm may be momentarily useless. Furthermore, the likelihood of hitting a target is often a function of how steadily the firearm is held during the aiming and firing of the firearm. In critical situations, accuracy may be lost due to premature firing.
With the advent of small-sized lightweight laser diodes, associated circuitry and power supplies, aiming devices for firearms incorporating lasers came about. The frequency of the emitted aiming laser beam may be within or outside the visible spectrum. To ensure correspondence between the aiming laser beam and the trajectory of the projectile, the aiming laser beam may be bore sighted, as is well known. Such bore sighting is accurate to a certain range, which is a function of the type and nature of projectile, muzzle velocity and barrel configuration of the firearm. Most laser or infrared aiming beams incorporate adjustments for elevation and windage as a function of the range to the target and ambient climatological conditions, whereby accuracy at substantial ranges can be achieved.
A primary benefit of a laser aiming device is that the target is identified with a dot visible with goggles or the naked eye depending on whether or not the frequency of the laser beam is within the visible spectrum. When the dot is on a target, the firearm may be fired in whatever position it may be at that moment with a reasonable expectation that the projectile will hit the target. Thus, visual alignment of the firearm is no longer mandatory. If the laser aiming device emits radiant energy in the non-visible frequency range, the target will be unaware that a firearm is being aimed at it/him/her; necessarily, the user of the firearm must wear goggles of a type that will permit viewing the laser beam irradiating the target.
Combat units and others using laser aiming devices with their firearms conduct training exercises simulating combat. These exercises usually involve aiming the laser aiming devices at personnel. Since some combat environments require power levels that could cause permanent damage to one""s eyesight unnecessary exposure to the likelihood of injury is present during training operations. To reduce the likelihood of injury during training, the power levels of the laser aiming devices must be prevented from exceeding a predetermined level (eye safe level). Usually, a switch on the laser aiming device permits selection of the output power at an eye safe level or at a maximum level. A danger of such prior art switches is that of inadvertently, by accident, or through forgetfulness, positioning the switch in the maximum power level position when it should be in the eye safe power level position. The resulting likelihood of injury to personnel of the opposing forces in a training exercise becomes very high and inexcusable.
Furthermore, the power output of laser diodes is essentially inversely proportional to temperature. When the output power is set at an eye safe level equal to or less than 0.7 milliwatts (mw) at a given ambient temperature, the power output may exceed this level upon a drop in temperature. To prevent the resulting possible hazard the output power should be prevented from increasing as a function of temperature. Thus, a benefit would be achieved if the laser aiming light maintained an essentially constant power output level irrespective of a drop of the ambient temperature.
When using laser aiming devices operating in the invisible spectrum, the user of the device must wear goggles of a type that will permit viewing of the irradiating laser beam. Far and away the most common of these devices is the class of night vision goggles that multiplies available light to produce an image of the scene being viewed. Because these devices operate on the principle of light amplification, under low light conditions such as under cloud cover or inside an enclosed structure, these devices are of limited use. Conversely, because of the ability of these devices to multiply available light thousands of times, any source of bright light in an otherwise low light scene will cause a bloom or glare similar of the kind encountered with an automobile""s headlights on a dark night. Because of this glare, the viewing scene becomes washed in glare and features are indistinguishable. This condition is aggravated with the decrease in ambient light. Furthermore, the scene viewed through night vision goggles is monochromatic and many lack depth of field provided by a stereo graphic image. As a result, it is often difficult to visually acquire a dim aiming dot amid a highly textured scene such as a brushy field. As a result of these limitations in night vision technology, combat personnel using these devices need laser aimers that can be variably adjusted to compliment the limitations of night vision goggles rather than aggravate them. Thus, the optimum laser aiming device would have a variable intensity aiming dot that could be adjusted for range and light conditions so as to eliminate any xe2x80x9cbloomxe2x80x9d. Also, the optimum laser aiming device would include auxiliary illumination in the IR (infrared) spectrum to augment available light in low light conditions and provide primary light in conditions where ambient light is unavailable. Finally, the optimum laser aiming device would include a means of causing the aiming dot to pulse in order to facilitate quick visual acquisition in highly textured scenes. An additional benefit would be realized if the laser aimer provided multiple pulse rates so a group of personnel could work together and know which aim point was their own.
To ensure that a laser aiming device has sufficient power in any foreseeable temperature excursion environments, a temperature compensating circuitry is employed to increase the power applied to an associated laser diode to compensate for the reduced efficiency of the laser diode as a function of temperature increase. Thereby, the radiated laser beam emitted will have sufficient power to illuminate a target with a dot of radiated energy within the range of the firearm irrespective of the ambient temperature. Conversely, when temperature decreases and the laser diode efficiency increases, the temperature compensation circuit reduces power applied so as to maintain eye safe emissions. A switch removable and replaceable only upon dismounting of the laser aiming device from the firearm, determines whether the output power is at an eye safe level or at a maximum power level. By installing an eye safe switch for training exercises, it is impossible for the laser aiming device to emit sufficient power to cause injury to the eyesight of any personnel involved in the training exercise. In a combat environment, a switch permitting full power is installed. Depending upon various considerations of use, a switching capability exists to select continuous or pulsating emissions at one or more rates to help detect the location of the target irradiating beam and a selection of the amount of area illumination of a target by a high power infrared light emitting diode. Furthermore, a capability exists to adjustably select the radiated laser beam brightness to compensate for variations in operating environments.
It is therefore a primary object of the present invention to provide temperature compensating circuitry for a laser aiming device which ensures a constant power output irrespective of changes in the ambient temperature which is of particular concern when the laser aiming device is used in an eye safe mode.
Another object of the present invention is to provide circuitry to compensate for temperature related reduced or increased efficiency of a laser diode in a laser aiming device.
Still another object of the present invention is to provide a captured removable fire switch for a laser aiming device.
Yet another object of the present invention is to provide a remotely operated removable switch for a laser aiming device that cannot be pulled loose.
A further object of the present invention is to require replacement of a removable fire switch to switch operation of the laser aiming device between an eye safe mode and a full power mode.
A still further object of the present invention is to provide removable fire switches that limit the maximum power output when the laser aiming device is operated in either the eye safe mode or in the high power mode.
A still further object of the present invention is to provide a rotary up-down control to adjust aiming dot brightness.
A still further object of the present invention is to provide rotary switch for selecting a continuous, slow pulse rate or fast pulse rate beam of a laser aiming device.
A still further object of the present invention is to provide the capability of selectively illuminating a target with a low or a higher intensity infrared LED as a light source.
A still further object of the present invention is to provide an integral rigid mounting system that allows the device to be quickly and accurately mounted and dismounted from a weapon.
A yet further object of the present invention is to provide a method for operating a laser aiming device in different environments.
These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds.